We in this article are providing you all with class 9 geography chapter 4 climate short notes along with the ncert solutions. Students will be able to get conceptual knowledge, the key terms related to the lesson climate, and ncert solutions. It will help them to solve the exercises and get the gist of the lesson. Let us start with discussing the short notes and terms related to the lesson Climate.
Climate refers to the sum total of weather conditions and variations over a large area for a long period of time (more than thirty years).
Weather refers to the state of the atmosphere over an area at any point in time.
The elements of weather and climate are the same and depend on many factors like temperature, atmospheric pressure, wind, humidity, and precipitation. On the basis of the monthly atmospheric conditions, the year is divided into seasons such as:
- Winter
- Summer
- Rainy Seasons
Climatic Controls
The climate of any place depends on the following factors:
1) Latitude
The amount of solar energy received varies according to latitude due to the position of the earth. That’s why air temperature generally decreases from the equator towards the poles.
2) Altitude
The atmosphere becomes less dense and temperature decreases when we go to the higher altitude from the earth’s surface. This is the reason why hills are cooler during summer.
3) Pressure and wind system
The pressure and wind system of any area depends on the latitude and altitude of the place. It influences the temperature and rainfall pattern.
4) Distance from the sea
As the distance from the sea increases, its moderating influence decreases and people experience extreme weather conditions. That is why it is very hot during summers and very cold during winters.
5) Ocean currents
Ocean currents along with onshore winds affect the climate of the coastal areas. For example, any coastal area with warm or cold currents flowing past it, will be warmed or cooled if the winds are onshore.
6) Relief features
Relief also plays a major role in determining the climate of a place. High mountains act as barriers to cold or hot winds that help to cause precipitation. Precipitation is any form of moisture that falls to the earth. It includes rain, snow, hail, and sleet.
Factors Affecting India’s Climate
Latitude
The Tropic of Cancer passes through the middle of the country from the Rann of Kachchh in the west to Mizoram in the east. India experiences tropical as well as subtropical climates.
Altitude
India has mountains to the north and also has a vast coastal area with a maximum elevation of about 30 meters.
Pressure and Winds
The climate and weather conditions in India are governed by the following atmospheric conditions:
- Pressure and surface winds
- Upper air circulation
- Western cyclonic disturbances and tropical cyclones
Air moves from the high-pressure area over the southern Indian Ocean, in a south-easterly direction, crosses the equator and turns right towards the low-pressure areas over the Indian subcontinent. These are known as the Southwest Monsoon winds.
These winds blow over the warm oceans, gather moisture, and bring widespread rainfall over the territories of India in the mid of July.
Jet streams are fast flowing, narrow, meandering air currents in the atmosphere.
The Indian Monsoon
The climate of India is strongly influenced by monsoon winds. The seasonal reversal of the wind system is known as “monsoon”. The monsoons are experienced in the tropical area roughly between 20° N and 20° S.
The differential heating and cooling of land and water create a low pressure on the landmass of India while the seas around experience comparatively high pressure.
- The shift of the position of the Inter-Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain, is also known as the monsoon-trough during the monsoon season.
- The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean affects the Indian Monsoon.
- The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of low pressure over the plateau at about 9 km above sea level.
- The movement of the westerly jet stream to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer also impact the Indian Monsoon.
The changes in the pressure conditions over the southern oceans also affect the monsoons. The irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean that affects the climate of the tropics and subtropics is known as Southern Oscillation or SO.
The Onset of the Monsoon and Withdrawal
The duration of the monsoon is between 100-120 days from early June to mid-September. Around the time of its arrival, the normal rainfall increases suddenly and continues constantly for several days, which is known as the “burst” of the monsoon.
The arrival of the Monsoon in different parts of India
The monsoon arrives at the southern tip of the Indian peninsula generally by the 1st week of June. It is divided into two – the Arabian Sea branch and the Bay of Bengal branch.
- The Arabian Sea and the Bay of Bengal branches of the monsoon merge over the northwestern part of the Ganga plains.
- Delhi receives the monsoon showers from the Bay of Bengal branch by the end of June.
- By the first week of July, western Uttar Pradesh, Punjab, Haryana, and eastern Rajasthan experience the monsoon.
- By mid-July, the monsoon reaches Himachal Pradesh and the rest of the country.
Withdrawal of the Monsoon
The withdrawal of the monsoon begins in the northwestern states of India by early September. By mid-October, it withdrew completely from the northern half of the peninsula. By early December, the monsoon had withdrawn from the rest of the country.
The Seasons
4 main seasons can be identified in India:
- The cold weather season (Winter)
- The hot weather season (Summer)
- The advancing monsoon (Rainy Season)
- The retreating monsoon with some regional variations (Transition Season)
Let’s discuss each of them in detail
The Cold Weather Season (Winter)
Winter begins from mid-November in northern India and stays till February.
- December and January are the coldest months in the northern part of India.
- The temperature decreases from south to the north.
- Days are warm and nights are cold.
- The weather is marked by a clear sky, low temperatures, and low humidity, and feeble, variable winds.
- This season is extremely important for the cultivation of ‘rabi’ crops.
The Hot Weather Season (Summer)
From March to May, hot weather is observed in India. The summer months experience rising temperature and falling air pressure in the northern part of the country. A striking feature of the hot weather season is the ‘loo’. Loo is the strong, gusty, hot, dry winds blowing during the day over the north and northwestern India.
Towards the close of the summer season, pre-monsoon showers come which help in the early ripening of mangoes, and are often referred to as ‘mango showers’ OR Kaal Baisakhi in west Bengal.
Advancing Monsoon (The Rainy Season)
South-east trade winds originate over the warm subtropical areas of the southern oceans.
They cross the equator and blow in a southwesterly direction entering the Indian peninsula as the southwest monsoon.
The monsoon winds cover the country in about a month. Mawsynram in the southern ranges of the Khasi Hills receives the highest average rainfall in the world.
A phenomenon associated with the monsoon is its tendency to have ‘breaks’ in rainfall due to the monsoon trough. The trough and its axis keep on moving northward or southward and determine the spatial distribution of rainfall.
The monsoon is known for its uncertainties. The alternation of dry and wet spells varies in intensity, frequency, and duration.
Retreating/Post Monsoons (The Transition Season)
The months of October-November form a period of transition from hot rainy season to dry winter conditions. The retreat of the monsoon is marked by clear skies and a rise in temperature. While day temperatures are high, nights are cool and pleasant. This is commonly known as ‘October heat’. In the second half of October, the mercury begins to fall rapidly in northern India.
Distribution of Rainfall
- Parts of the western coast and northeastern India receive over about 400 cm of rainfall annually.
- Rainfall is less than 60 cm in western Rajasthan and adjoining parts of Gujarat, Haryana, and Punjab.
- Snowfall is restricted to the Himalayan region.
- The annual rainfall is highly variable from year to year.
Monsoon as a Unifying Bond
The unifying influence of the monsoon on the Indian subcontinent is quite noticeable. The seasonal alteration of the wind systems and weather conditions provide a rhythmic cycle of seasons.
The uncertainties of rain and uneven distribution are very much typical of the monsoons. Year after year, people of India from north to south and from east to west, eagerly await the arrival of the monsoon. These monsoon winds bind the whole country by providing water to set the agricultural activities in motion.
NCERT Solutions For Class 9 Geography Chapter 4 Climate
1. Choose the correct answer from the four alternatives given below.
(i) Which one of the following places receives the highest rainfall in the world?
(a) Silchar
(b) Mawsynram
(c) Cherrapunji
(d) Guwahati
Answer (b) Mawsynram
(ii) The wind blowing in the northern plains in summers is known as:
(a) Kaal Baisakhi
(b) Loo
(c) Trade Winds
(d) None of the above
Answer (b) Loo
(iii) Which one of the following causes rainfall during winters in the north-western part of India.
(a) Cyclonic depression
(b) Retreating monsoon
(c) Western disturbances
(d) Southwest monsoon
Answer (a) Cyclonic depression
(iv) Monsoon arrives in India approximately in:
(a) Early May
(b) Early July
(c) Early June
(d) Early August
Answer (c) Early June
(v) Which one of the following characterizes the cold-weather season in India?
(a) Warm days and warm nights
(b) Warm days and cold nights
(c) Cool days and cold nights
(d) Cold days and warm nights
Answer (c) Cool days and cold nights
2.Answer the following questions briefly.
(i) What are the controls affecting the climate of India?
There are six major controls affecting the climate of any place. They are: latitude, altitude, pressure and wind system, distance from the sea, ocean currents, and relief features
(ii) Why does India have a monsoon type of climate?
Jet Stream, Coriolis Force, InterTropical Convergence Zone (ITCZ), El Nino are some of the reasons why India has a monsoon type of climate.
(iii) Which part of India does experience the highest diurnal range of temperature and why?
In the Thar Desert of Rajasthan of India, the day temperature may rise to 50°C, and drop down to near 15°C the same night.
(iv) Which winds account for rainfall along the Malabar Coast?
South-West Monsoon Winds.
(v) What are Jet streams and how do they affect the climate of India?
Jet streams are narrow belts of high altitude (above 12,000 m) westerly winds in the troposphere. Their speed varies from about 110 km/h in summer to about 184 km/h in winter.
(vi) Define monsoons. What do you understand by “break” in monsoon?
The word monsoon is derived from the Arabic word ‘mausim’ which literally means season. ‘Monsoon’ refers to the seasonal reversal in the wind direction during a year. The monsoon rains take place only for a few days at a time. They are distributed with rainless intervals. These are known as “break” in monsoon.
(vii) Why is the monsoon considered a unifying bond?
- The Himalayas act as a barrier and protect us from the cold winds from Central Asia. Like this, the peninsular plateau is also covered from three sides and has moderate temperatures.
- Monsoon is considered a unifying bond and with its seasonal alteration, it provides the rhythmic cycle of seasons. The uncertainties and varied distribution depend on the monsoon type climate of India.
- The monsoon-type climate also helps our country to boast its flora fauna and other species. Our many festivals and crop patterns also depend on it.
- People from all over the country wait eagerly for it as it provides motion to the agricultural activities.
- Why does the rainfall decrease from the east to the west in Northern India?
The Bay of Bengal branch of the monsoon winds moves towards the northeast and returns westwards covering the northern plains. While they move towards the west, their moisture content tends to reduce with subsequent rains. Hence the rainfall decreases from east to west in northern India.
Q4. Give reasons as to why.
(i) Seasonal reversal of wind direction takes place over the Indian subcontinent?
(i) El Nino has a major role to play in the seasonal reversal of wind direction over the Indian subcontinent.
(ii) The bulk of rainfall in India is concentrated over a few months.
(ii)The monsoon begins from the first week of June and advances quite rapidly to cover almost the whole country by mid-July. Hence, the bulk of rainfall in India is concentrated over the months of a few months; mainly June to August.
(iii) The Tamil Nadu coast receives winter rainfall.
(iii)The Tami Nadu coast receives winter rainfall because of the movement of low-pressure conditions to the Bay of Bengal.
(iv) The delta region of the eastern coast is frequently struck by cyclones.
(iv) The Bay of Bengal is the center of various pressure changes and hence there is always a chance of cyclone development.
(v) Parts of Rajasthan, Gujarat, and the leeward side of the Western Ghats are drought-prone.
(v)The parts fall in the rain shadow area of the Aravalli. Hence, they are drought-prone and don’t receive much rainfall.
Q5. Describe the regional variations in the climatic conditions of India with the help of suitable examples.
Answer :
- There is regional variation in the climatic conditions of India. Temperature and Precipitation vary from place to place and season to season.
- In summers the temperature rises up to 50°C in parts of Rajasthan, whereas it may be around 20°C in Pahalgam in Kashmir. This shows huge differences and effects like this.
- In winter, the night temperature in Drass valley of Kashmir may be minus 45°C, whereas in Thiruvananthapuram in Kerala it may have a temperature of 20°C.
- In the Andaman Islands, the difference between day and night temperature may be hardly 7° – 8°C.
- Coastal areas experience less contrast in the temperature, whereas seasonal contrasts are more in the interior of the country.
- There is a decrease in rainfall generally from east to west in the northern plains.
- Most parts of India get rainfall from June – September, whereas the Coromandel Coast gets rainfall in the winter season.
Q6. Discuss the mechanism of monsoons.
Following are the factors responsible for the mechanism of monsoon:
The duration of the monsoon is between 100-120 days from early June to mid-September. Around the time of its arrival, the normal rainfall increases suddenly and continues constantly for several days, which is known as the “burst” of the monsoon.
The monsoon arrives at the southern tip of the Indian peninsula generally by the 1st week of June. It is divided into two – the Arabian Sea branch and the Bay of Bengal branch.
- The Arabian Sea and the Bay of Bengal branches of the monsoon merge over the northwestern part of the Ganga plains.
- Delhi receives the monsoon showers from the Bay of Bengal branch by the end of June.
- By the first week of July, western Uttar Pradesh, Punjab, Haryana, and eastern Rajasthan experience the monsoon.
- By mid-July, the monsoon reaches Himachal Pradesh and the rest of the country.
Q7. Give an account of weather conditions and characteristics of the cold season.
Following are the features of the cold season:
Winter begins from mid-November in northern India and stays till February.
- December and January are the coldest months in the northern part of India.
- The temperature decreases from south to the north.
- Days are warm and nights are cold.
- The weather is marked by a clear sky, low temperatures, and low humidity, and feeble, variable winds.
- This season is extremely important for the cultivation of ‘rabi’ crops.
Q8. Give the characteristics and effects of the monsoon rainfall in India.
Characteristics of the monsoon rainfall in India:
- The duration of the monsoon varies from 100 to 120 days from early June to mid-September.
- The normal rainfall increases suddenly and continues regularly for several days. This is called the ‘burst’ of the monsoon.
- They are distinguished from the pre-monsoon showers because of their increase in rainfall amount and regularity.
- The monsoon arrives at the southern tip of the Indian Peninsular generally by the first week of June.
- The rainfall is unevenly distributed across the country.
Effects of the monsoon rainfall in India:
- Agriculture in India largely depends on Indian monsoons for water. Late, Low or excessive rains have a negative impact on crops.
- Due to the uneven distribution of rainfall across the country, there are few places that are drought-prone and few are flood-affected.
- The monsoon provides India with a diverse climatic pattern. Hence, in spite of the presence of great regional variations, it has a unifying influence upon the country and its people.
Conclusion
To conclude, we have penned down all the relevant short notes of class 9 geography chapter 4 Climate along with the NCERT Solutions. Students would get help to know the factual questions as well as to gain conceptual understanding. Stay updated with cbseguides.com for more such content.
